EAP 7 MultipartParser doesn't properly handle multi-line headers

Issue

• According to section 2.2.3 of RFC2822, headers may be folded at a whitespace character with a CRLF. Currently, MultipartParser considers the CRLF the end of the header value in all cases rather than checking for a whitespace character that signals the continuation of the value. This results in a MalformedMessageException to be thrown from the headerName method when the currentString (which now contains the remainder of the value) is checked to ensure it is null.